The present embodiments relate to transmission of an intermediate frequency signal and an oscillator signal for mixing down the radio-frequency receive signal into an intermediate frequency level.
Magnetic resonance tomographs are imaging apparatuses that, for imaging an examination object, align nuclear spins of the examination object with a strong external magnetic field and excite the nuclear spins by a magnetic alternating field for precession around this alignment. The precession or return of the spins from this excited state into a state with lower energy generates a magnetic alternating field as a response (e.g., a magnetic resonance signal) that will be received via antennas.
With the aid of magnetic gradient fields, a spatial encoding is impressed onto the signals, which subsequently makes it possible to assign the received signal to a volume element. The received signal is then evaluated, and a three-dimensional imaging representation of the examination object is provided.
To excite the precession of the spins, magnetic alternating fields with a frequency that corresponds to the Larmor frequency at the respective static magnetic field strength and very high field strengths or powers are to be provided. To improve the signal-to-noise ratio of the magnetic resonance signal received by the antennas, antennas that are often referred to as local coils and are arranged directly on the patient may be used.
For imaging, the magnetic resonance signals received by the local coil are transmitted to a receive device of the magnetic resonance tomograph. The magnetic resonance signals may also be stepped down by mixing the magnetic resonance signals into a lower frequency range (e.g., intermediate frequency). In order to be able to detect the phase and frequency features of the original magnetic resonance signal during evaluation, the mixing signal or oscillator signal is then likewise to be provided as a reference and is to be transmitted.
The magnetic resonance signal may have a bandwidth of one Megahertz. Once the magnetic resonance signal has been mixed down to an intermediate frequency of, for example, 10 MHz, the intermediate frequency signal consequently involves a relatively wideband signal.
Coaxial cables that, in thin and flexible forms of embodiment, for example, are expensive and difficult to work with may be used for transmission of the signals.
The published patent DE 10104260 A1 discloses a symmetrizing element for two frequencies. The published patent DE 102013209450 A1 describes a symmetrizing element for a widened frequency range.